The Big East introduced Boise State, San Diego State, Houston, SMU and Central Florida as its newest members, effective 2013.

‘‘The Big East conference is the first truly national college football conference,’’ Commissioner John Marinatto said Wednesday during a teleconference with the university leaders from the five schools. Boise State President Bob Kustra said the announcement was ‘‘a significant step forward in the evolution of Boise State University and our football program.’’

The Big East, depleted by the planned departures of Syracuse, Pittsburgh and West Virginia, is trying to rebuild as a 12-team football conference with a western division.

It’s been a slow process that began in September, and there is still work to be done.

Boise State and San Diego State, which currently play in the Mountain West Conference, will join the Big East only for football. Houston, SMU and UCF will be leaving Conference USA and joining the Big East in all sports.

‘‘We have ambitious plans, and this expansion is a great stride toward reaching them,’’ Marinatto said.

The Big East has also been pursuing Air Force and Navy as football only members, but it seems Air Force is no longer a possibility. Lt. Gen. Mike Gould, the superintendent of the academy, said the school will stay in the Mountain West.

‘‘We belong out West and for now that’s where we’re going to stay,’’ he told the AP.

Boise State has reportedly worked out a deal to have its other sports teams compete in the Western Athletic Conference, where its football team dominated for 10 seasons. San Diego State is reportedly finalizing a deal to have its other teams compete in the Big West.

The Big East has only five football members committed to the conference beyond this season: Connecticut, Cincinnati, Louisville, Rutgers and USF. It also has seven schools that do not play major college football and Notre Dame, which competes in the Big East in everything but football.

Marinatto has pledged to hold Pittsburgh, Syracuse and West Virginia in the conference until 2014, in accordance with the Big East bylaws. West Virginia wants to join the Big 12 in 2012 and has sued the Big East to get an early release.

The Big East filed a countersuit to keep West Virginia in the conference. Pittsburgh and Syracuse intend to join the Atlantic Coast Conference as soon as possible, but are not challenging the Big East’s bylaws.

Syracuse athletic director Daryl Gross said he expected the Big East might ask his school and Pitt to leave early now.

‘‘They’d need us to move out of the way,’’ said Gross, who was taking part in IMG’s Intercollegiate Athletics Forum in Manhattan on Wednesday.

Marinatto said there have been no discussions with the new members about the possibility of letting the departing members out early. Potentially, that could lead the Big East to have the same eight teams it has now in 2012 and as many as 15 members in 2013.

‘‘I think it’s a simple matter of respecting our bylaws,’’ Marinatto said of having lame duck members. ‘‘An early departure and a violation of those bylaws would damage the membership.’’

The Big East was born in 1979 as a northeast basketball conference and in 1991 added football with the inclusion of Miami, Virginia Tech and others.

Maintaining a strong football league has been difficult. Miami, Virginia Tech and Boston College left the Big East for the ACC in 2004 and ‘05, and the league seemed on the verge of extinction.

Instead, it expanded, bringing in Louisville, Cincinnati, South Florida, DePaul and Marquette.

The additions revitalized the football league for a few years and Big East basketball, with 16 members, has been better than ever.

The latest additions are all about football and television markets. Boise State has been one of the most successful programs in the country over the last decade playing mostly in the Western Athletic Conference before joining the MWC this season.

The Broncos are 72-6 over the last five seasons with two BCS victories.

Houston has been to a bowl game six of the last seven seasons, and is in the 10th-largest television market in the country, according to Nielsen. San Diego State, UCF and SMU have all been on the upswing on the field in recent years.

Just as importantly, Dallas, where SMU is located, is the fifth-largest TV market. Orlando, where UCF is located, is in the 19th largest, and San Diego is the 28th largest.

Marinatto said the additions boost the Big East’s potential TV households by more than six percent and up to 28 million. He added that having members in four time zones would allow the league to play four games on a Saturday that don’t overlap.

The Big East is hoping that a combination of success on the field and potential viewers will help the league land a new television deal that can keep it relatively competitive with the other power conferences, all of which have signed long-term TV contracts worth more than $1 billion.

‘‘This new footprint is the largest footprint in all of college sports,’’ Marinatto said.

The five new members are banking on the move to the Big East bringing increased TV revenue and exposure, along with better access to the Bowl Championship Series and its multimillion-dollar payouts.

‘‘This is a game-changer for us,’’ University of Houston President Renu Khator said. Getting to the BCS has been a particular problem for Boise State. For the second straight season, Boise State went 11-1 and ranked among the top teams in the country but was left out of the marquee bowl games.

‘‘That clearly was one of the reasons that drove us toward this decision,’’ Kustra said.

‘‘So there’s no question that we’ve been frustrated over recent years as to how the BCS has handled those who were not automatic qualifiers. But the time has come for us to deal with what we can control and not worry about the rest. I think it’s fair to say that that’s the reason why I’m on this teleconference today.’’

The Big East has an automatic bid to the BCS through the 2013 season. But the future of the BCS is unclear and whether the Big East holds onto its AQ-status, or whether there will even be such a thing after 2013, is unknown.

Meanwhile, the leagues Boise and the rest are leaving behind have already announced in October they would be merging. Conference USA and the Mountain West announced in October they would create a far-flung football league with as many as 22 teams by 2013.

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AP Sports Writers Rachel Cohen in New York and Pat Graham in Beaver Creek, Colo., contributed to this report.